Imprinting technique is a process to press a mold on which a recessed and projected pattern has been formed, on a liquid resin or the like present on a substrate, thereby transferring the pattern of the mold into the resin. The recessed and projected pattern has a size ranging from a nano scale of a 10 nm level to about 10 μm. This technique has been applied in various fields including semiconductor materials, optical materials, recording media, micromachine, biology, and environment.
Exemplary imprinting includes heat imprinting and photo-imprinting. In the heat imprinting, a mold on which a prescribed form has been formed is press-contacted with a thermoplastic resin prepared by melting at a glass transition temperature or higher, thereby heat-imprinting the surface form of the mold into the thermoplastic resin, and after cooling, the mold is detached. In the photo-imprinting, a mold as described above is pressed on a photo-curable resin and the photo-curable resin is cured by an energy ray such as ultraviolet ray, and then the mold is detached.
On the other hand, as a mold, quartz, silicon, or the like is usually used in view of strength, hardness, processability, dimensional stability, etc. These materials, however, have problems such as fragility, expensiveness, and time-consuming for their preparation. In order to overcome these problems, these molds, e.g., quartz, are used as a master mold to prepare a replica mold to thereby deal with mass production.
As the replica mold, a resin mold has been known in view of versatility and cost. In obtaining the resin replica mold from a mother pattern composed of a resin obtained from the master mold, good compatibility between the resins, namely between the surface of the mother pattern and the surface of the replica mold, made it difficult to release the replica mold from the mother pattern. There is thus a report of using a specific resin to achieve releasability (for example, Patent document 1). However, resins employable for the replica mold were limited and thus this led to poor versatility. Moreover, there was no report on releasability of the replica mold in the case of using the replica mold for the imprinting into a resin.
Meanwhile, to allow a mold to have releasability from the resin subjected to imprinting, it is known to apply a coupling agent, such as a silane coupling agent, as a release agent, onto a transfer type surface of a glass substrate or the like, thereby making a surface energy of the mold be within an appropriate range to achieve releasability (for example, Patent document 2). However, the difficulty in the release agent adhering onto the transfer type surface caused problems, such as the peeling of the release agent, and the difficulty in controlling the thickness of the release agent layer to prevent the peeling.
A further example of a mold having releasability from a resin subjected to imprinting is a mold provided with a photo-catalyst layer formed on a substrate, the photo-catalyst layer being composed of two layers and having a recessed and projected surface, thereby the photo catalytic performance decomposing adhesive power and bonding power between the mold and the resin subjected to imprinting. In this mold, furthermore, the photo-catalyst performance decomposes an organic material lying between the photo-catalyst layer and the surface of the cured resin subjected to imprinting, thereby making it easy to remove a contamination from the mold (for example, Patent document 3). However, the two-layer structure of the photo-catalyst layer makes the resultant mold have a poor flexibility. Furthermore, since this process relies on the photo-catalyst performance to achieve the releasability, resins to be subjected to imprinting are limited to photo-curable resins.